Tool for stripping insulation from electric cables



Nov. 2, 1965 D. s. STALLINGS 3,2 5, 07

TOOL FOR STRIPPING INSULATION FROM ELECTRIC CABLES Filed June 14, 1963 2 Sheets-Sheet 1 J7 4; //& INVENTOR iazqgles ,5. fiiaZZzkgy;

' ATTORNEY 1965 D. s. STALLINGS 3,215,007

TOOL FOR STRIPPING INSULATION FROM ELECTRIC CABLES Filed June 14, 1963 2 Sheets-Sheet 2 INVENTOR iazgZaa ,5: ,fiiailz'rgs ATTORNEY United States Patent 3,215,097 TOOL FOR STRIPPING INSULATION FROM ELECTRIC CABLES Douglas S. Stallings, 353 Best Gate Road, Annapolis, Md. Filed June 14, 1963, Ser. No. 287,932 9 Claims. (Cl. 81-95) This invention relates to tools for stripping insulation from electric cables, particularly of the type of insulating sheathing of hard plastic or other hard forms of insulation, which have been found difficult to remove.

The primary object of the present invention is to provide certain improvements to the tool covered by application S.N. 266,438 filed March 19, 1963, for Insulation Stripping Tool. While the tool disclosed herein is basically the same as that in said earlier application, the improvements herein relate to added features which facilitate the operation of the tool both in the cutting and stripping of the insulation sections.

As in the earlier application, this invention provides for a hand tool comprising a pair of pivotally connected hand lever elements, one provided with a cutter assembly and the other a cable supporting assembly, which assemblies cooperate for both circumferential and longitudinal cuts in the cable insulating sheathing and gripping elements for removing the cut sections of the sheathing.

The improvements, according to the present invention, include an adjusting element for clamping the tool on the cable for making the maximum cut in a single operation if desired, although preferably it may be set for two or more successive cuts of increasing depths to the full depth as provided for by a backlash and spring operation for effecting the cut to its maximum depth through the sheathing, whereby a more uniform cut is achieved without penetrating the metal cable and with greater case. This adjusting element not only provides for a constant gripping on the cable, or cables of different sizes throughout the range of operation of the tool but when set to grip the cable it remains in place without the operator having to hold it. The adjusting element also provides for a minimum closing of the tool as well as a maximum opening thereof and does not interfere with the manual closing of the tool down to the minimum closing position in case, in some instances, it is not desired to employ the adjusting element.

Another improved feature of this invention includes the positioning of the stripping grippers inward of the ends of the hand lever elements close to the cable cutting and supporting assemblies where there is less danger of injury to the operator and also affords greater leverage for gripping and stripping operations. In this respect, the adjustable clamping member being fixed for a minimum closing of the tool prevents these grippers from close engagement which might catch a finger or glove of the operator of the tool.

While the tool in accordance with the present invention has all the advantages of that disclosed in said earlier filed application, it is clear that the improvements herein have decided advantages-increasing the range over which the tool can operate as well as others pointed out above and as will appear hereinafter. Further objects and details of my invention will appear in the following specification and accompanying drawings forming a part thereof.

In the drawings:

FIG. 1 is a side elevation of an insulating sheathing cutter and stripping hand tool showing a cable in position for a circumferential cutting operation on the cable sheathing.

FIG. 2 is a top plan view thereof.

FIG. 3 is an end elevation view of a left hand end of Patented Nov. 2, 1965 the tool shown in FIG. 1 and FIG. 2 showing a cable in position for a longitudinal cut.

FIG. 4 is a plan View of a blank from which the lower handle and bucket are formed.

FIG. 5 is a longitudinal sectional view taken on line 55 of FIG. 2.

FIG. 6 is a cross sectional view taken on line 6-6 of FIG. 1.

The stripping tool to which the present improvements are applied is basically the same as that covered in said earlier application referred to. It includes upper and lower hand lever elements 10 and 11 respectively pivotally connected at 12 and carrying cutter and cable supporting assemblies 13 and 14. These assemblies cooperate for cutting the sheathing 15 on a conductor cable 16 which, as shown in FIG. 1, is positioned for a circumferential cut into the sheathing 15 and in FIG. 3, a longitudinal cut. A flat type spring element 17 mounted in upper handle lever 10 and associated with an adjustable clamping element link 43, hereinafter described, operates to yieldingly urge the levers 10 and 11 to an open position. Handles 10 and 11 are provided with gripping elements 18 adjacent to the cutter and supporting assemblies for the stripping of the cut portions of the cable insulation; this affords an improvement over the arrangement where the grippers are at the outer ends of the levers both as to safety and operating efliciency as will appear hereinafter.

The cutter assembly 13, or interchangeable operating heads, includes a cylindrical support 20 extending laterally from lever 10, preferably detachably secured by means of a reduced portion 21 thereof extending through corresponding apertures in both side portions 10a and 10b of handle lever 10 with a spacing sleeve 211 thereon between the side portions and secured in place by means of a nut 23. Adjacent to the outer end of support 20 is a kerf 24 in its lower side portion for receiving a disk cutter 25 which is mounted on a pivot bolt 26 extending into the end of the support. As in said earlier application, this mounting 20 is quite close to the lever pivot 12 so that the cutter disk 25 projects downwardly to a position between the rollers 36 of the cable supporting assembly 14.

In order to limit the depth of cut by disk 25 a cylindrical housing member 30 is formed with an eccentric bore to fit and bear on cylindrical support 20. A kerf 32 provides an opening through which cutter disk 25 may project, the amount of such projection beyond adjusting member 30 being determined by the position to which member 30 is turned, from a maximum to a position to substantially encase the disk where it can do no damage or not be damaged itself. Member 30 is retained in place by the assemblage of the disk cutter in the mounting support 20 and a screw 33 secures the cylindrical depth of cut adjusting member 30 in any selected position.

The cable supporting assembly 14 includes a channel support member, or bucket 35 formed to extend laterally from lower lever 11 and has a pair of grooved rollers 36 mounted on pivots 37 extending through the sides of the channel members 35 and at least one of which projects through both sides 11a and 11b of lever 11. Rollers 36 function the same as the cable supporting rollers in said earlier application, but are formed for a greater range of cable sizes.

Both lever members 10 and 11 are preferably formed from eighth-inch steel stock blanks, shaped, drilled and pressed to form the handle members. Lower lever 11 and bucket 35, as shown in FIG. 4, are formed from a single piece blank, the bucket portion extending from the pivoted end of the handle portion 11 in the form of an end extension 351 and thence backward parallel with the handle to provide an outer side portion 352 with a bottom 353 and inner side portion 354 for engaging the outer sidewall 11a of the handle. The blank is appropriately drilled as indicated by the same reference numerals for receiving lever pivot member 12, the roller pivots 37 and for other elements in connection with the tool. The bucket, 35, and handle, 11, are mainly held in assembled relationship and strengthened by means of the roller pivots 37. The end extension 351 being depressed at 355 so as not to interfere with a cable 15 supported by rollers 36, the cross-sectional area of this portion is maintained by a lower extension 356 which is provided with a slot 357 for engagement with an operators belt clamp. It will be noted that all these portions are provided in an integral blank, thereby increasing the strength of the handle as well as the bucket when assembled with a saving in material and production costs.

The present improvements include a clamping element link 43 shown in sectional view, FIG. 5, which consists of a relatively thick plate to provide the strength required for its operating functions and also reinforces the levers and 11. It is pivoted at 44 to lower lever 11 below its pivotal connection 12 with upper lever 10 and extends upwardly beyond pivot 12. The upper portion of link 43 is provided with a slot 45 through which an abutment pin 46 secured in a reduced end portion of the upper lever 10 extends and is engageable by the side walls and an end of the slot. This plate has an extension portion 38 engageable with the end of spring 17 which in turn urges the side wall 39 of the slot into engagement with the pin to yieldingly swing the levers 10 and 11 to their open position. The lower end 47 of this slot limits the maximum opening position of the levers 10 and 11 to a little greater than the maximum size of cable in the range for which the tool is constructed. While. the upper end of this slot could determine the extreme of the closing position, before the pin reaches this end of the slot the side 48 of link 43 engages the lever pivot 12 to positively stop the closing of the levers to a position so that the gripper teeth 18 are at a sufiicient distance apart so that they will not injure an operator of the tool or any of his apparel, or the like. Engagement of abutment pin 46 with side wall 49 of the slot 45 provides for variable adjustment of the closing of the levers 10 and 11 with respect to sizes of cables being operated upon by the cutting element, that is the grip thereon. For this adjustment clamping element 43 has its lower end portion 50 extending downwardly below its pivotal connection at 44 with lower lever 11 and is engaged by an element such as a cam for rocking or holding the link 43 on its pivot; this cam element is preferably in the form of a screw 51 extending through the lower portion of the channel lever 11 through a threaded element 52 therein between roller pivots 37 and there beyond is guided in a crimped portion 53 in lever handle 11. Screw 51 terminates beyond the end of lever 11 in a relatively large operating head 54 by which the adjustment of the opening of the levers is achieved and also provides an abutment to prevent slippage of the handle of the operator from the operating handle lever elements.

While the present tool is substantially the same size and dimensions of that disclosed in said earlier application, the present improvements provide a standard tool having somewhat greater range, of even less than a half-inch and up to about an inch and a quarter. This is attributed to a great extent to the smoother operation of the tool which is clamped in position for cutting operations of uniform depths. In the operation of the tool the clamping element provides a safety margin of the cutting action of the tool when gripping handles 10 and 11 are locked in position with locking screw 51 and plate 43 in a manner to provide a slight tension of spring holding the cutting disk into the cut. As the cut is made, the cutting disk tends to push away from the cut for the first cut, which is provided for by play of pin 46 in slot 45, the slot being slightly wider than the diameter of the pin, the excess in the width of the slot determining the amount of backoff of the cutting disk for the first cut being made. For a succeeding circumferential, or longitudinal cutting operation the spring loaded handles allow the cut to be made to the maximum depth required, as provided for by the pressure of spring 17 on plate 43. This procedure allows the depth of cut of the tool to be set simply by exposing the blade to maximum extent, gripping the wire or cable until the cutting action through the sheathing comes into contact with the wire cable 15 and the locking device set in this position and for this depth of cut eccentric head 30 may be set at this time and will remain set for subsequent cuts on cable of the same size. The cut may be accomplished by a single operation with the clamping member set for the maximum cut into the sheathing and tightened to overcome the pressure of spring 17. Removal of the cut sections of the sheathing by means of the grippers 18 which are pressed into longitudinal cuts in opposite sides of the cable and given a lateral twist to separate the sheathing sections is facilitated by the positioning of the gripper teeth close to the pivotal connection of the levers. In accordance with this arrangement the danger of the teeth at the end of the handles and the closing of the teeth upon each other has been eliminated.

In the claims, I have referred to the cutting or stripping of insulation or sheathing which shall be considered as synonymous. It is to be noted that in actual practice the tool operates equally efficiently on rubber insulation as well as the high density polyethyl plastics, and is also equally efiicient in cutting through lead sheathing as well as the plastic and other insulating materials. The tool is useful for both electric cables and telephone cables wherein it has been found to cut through. the sheathings without injuring the insulation coverings on the multiplicity of small conductors encased therein. The efficiency of the tool and improvements in their ease of operation and time saving in their accomplishments have been a revelation to field operators who have used the tool or witnessed its ease of operation as compared with any process or tool thus far devised.

Having set forth details of certain improvements in the stripping tool I claim broadly:

1. A tool for stripping insulation sheathing from an electric cable comprising a pair of pivotally connected levers, one having a cable supporting assembly, and the other carrying a sheathing cutting assembly with a cutting blade extending toward said supporting assembly, a link pivotally connected with one of said levers engageable with the pivotal connection of the levers for limiting the closing position of the levers and having a pin and slot connection with the other lever limiting the maximum opening position of the levers with respect to each other, and means cooperating with said link for adjusting and limiting the open position of the levers to position them in accordance with the size of the cable to be operated upon between the aforesaid opening and closing positions of the levers.

2. A tool for stripping insulation sheathing from an electric cable comprising a pair of pivotally connected levers, one having a cable supporting assembly, and the other carrying a sheathing cutting assembly with a cutting blade extending toward said supporting assembly, a link pivotally connected with one of said levers engageable with the pivotal connection of the levers for limiting the closing position of the levers and having a pin and slot connection with the other lever limiting the maximum opening position of the levers with respect to each other, and means cooperating with said link for adjusting and limiting the open position of the levers to position them in accordance with the size of the cable to be operated upon between the aforesaid opening and closing positions of the levers comprising a screw extending longitudinally through one of the levers and having its inner end engageable with saidt link for variably adjusting the extent of the open position of the levers.

3. A tool for stripping insulation sheathing from an electric cable comprising a pair of pivotally connected levers, one having a cable supporting assembly, and the other carrying a sheathing cutting assembly with a cutting blade extending toward said supporting assembly, a link pivotally connected with one of said levers and having a pin and slot connection with the other lever limiting the opening and closing positions of the levers with respect to each other, a spring cooperating with said link and one of the pivoted levers for yieldingly urging the levers to their open position, and manually controlled operating means cooperating with the link for holding the levers against opening when a cable is placed on the supporting assembly and the levers are closed on the cable with the cutting assembly blade penetrating the sheathing to the desired depth.

4. A tool for stripping insulation sheathing from an electric cable comprising a pair of pivotally connected levers, one having a cable supporting assembly, and the other carrying a sheathing cutting assembly with a cutting blade extending toward said supporting assembly, a link pivotally connected with one of said levers and having a pin and slot connection with the other lever limiting the opening and closing positions of the levers with respect to each other, a spring cooperating with said link and one of the pivoted levers for yieldingly urging the levers to their open position by pressing one side of said slot in the lever against the pin, and manually controlled operating means cooperating with the link for holding the levers against opening when a cable is placed on the supporting assembly and the levers are closed on the cable with the cutting assembly blade penetrating the sheathing to the desired depth, said slot being slightly wider than the pin so that upon starting a cutting operation the link shifts so that the pin engages the other side of the slot effecting a small back off of the cutting blade for an initial cut into the sheathing and the succeeding cut will be spring loaded with the spring operating to return the link to effect maximum depth of cut.

5. A sheathing stripping tool in accordance with claim 4 wherein the manually controlled operating means may be set to eliminate the back-01f movement of the cutter in order to effect the maximum depth of cut into the sheathing in a single cutting operation of the tool.

6. A tool for stripping insulation sheathing from an electric cable comprising a pair of pivotally connected levers, one having a cable supporting assembly, and the other carrying a sheathing cutting assembly with a cutting blade extending toward said supporting assembly, means associated With the cutting blade for adjustably limiting its depth of penetration of the blade into the sheathing to avoid cutting into the metal cable, a link pivotally connected with one of said levers and having a pin and slot connection with the other lever limiting the opening and closing positions of the levers with respect to each other, a spring cooperating with said link and one of the pivoted levers for yieldingly urging the levers to their open position by pressing one side of said slot in the lever against the pin, and manually controlled operating means cooperating with the link for holding the levers against opening when a cable is placed on the supporting assembly and the levers are closed on the cable with the cutting assembly blade penetrating the sheathing to the desired depth, said slot being slightly wider than the pin so that upon starting a cutting operation the link shifts so that the pin engages the other side of the slot effecting a small back oil? of the cutting blade for an initial cut into the sheathing and the succeeding cut will be spring loaded with the spring operating to return the link to effect a maximum depth of cut, as determined by said blade depth of cut limiting means.

7. A tool for stripping sheathing from a cable, including a core comprising: a pair of pivotally connected levers, a link pivotally connected with one of said levers, said link having a slot, a pin on the other of said levers and engaging said slot for limiting the closed position of the levers, said levers each having a pair of sheathing gripping teeth located as close to the pivotal connection of the levers as will permit a maximum sized cable to be operated upon by the tool with the levers extending therebeyond as handle members, the distance between the teeth on each lever at the closed position being slightly greater than a diameter of a core of a minimum sized cable, the teeth on each lever engaging opposite slits in a sheathing to pry same apart.

8. A cable stripper supporting assembly including, a lever member and a cable-supporting bucket member, both of said members being of channel configuration in cross-section, said members extending in side-by-side relation with adjacent legs of the channels in face-toface contact, said lever member extending beyond one end of said bucket member and constituting .a handle, an outer leg of said bucket at the other end thereof extending transversely inwardly to join a leg of said lever member to provide an integral connection between said members, means located in said bucket cable supporting member extending between the legs thereof, and a pin extending through said bucket legs, said cable supporting means and said lever member to secure said members and said supporting means in the assembled position.

9. A tool head and cutter for an electrical cable sheathing stripper including a pair of lever members pivotally connected at one end, one lever member having a laterally extending cable support and the other lever member having a transverse opening therethrough, a tool head extending laterally above the cable support, said tool head having an end portion extending through said lever opening and having a detachably secured connection with said other lever member, said tool head having a cylindrical outer end portion with a transverse kerf extending upwardly 'from its lower surface, a circular cutting element pivotally mounted in said kerf so as to project downwardly therefrom toward said cable support, a cylindrical depth of cut adjusting member having an eccentric bore therethrough rotatably mounted on said tool head cylindrical outer end portion and having a kerf therein through which said circular cutter may project to a maximum distance variably to a position in which it is substantially closed oiT from a cutting condition, and means for securing said depth of cut adjusting member in position for any required depth of cut.

References Cited by the Examiner UNITED STATES PATENTS 562,097 6/96 Rieckel. 653,364 7/00 Pittavino 81334 669,721 3/01 Bruce. 964,600 7/ 10 Adams. 1,208,694 12/ 16 Swickard 81-395 X 1,283,917 11/18 Rohne. 1,670,250 5 28 Froschhauser. 1,728,619 9/ 29 Lambert 30-296 2,3 00,087 10/42 Annello. 2,659,140 11/53 Davison. 2,817,255 12/57 Lormeau.

FOREIGN PATENTS 588,519 2/ 25 France. 1,123,431 6/56 France.

109,397 3/ 00 Germany. 588,777 11/ 33 Germany.

WILLIAM FELDMAN, Primary Examiner. 

1. A TOOL FOR STRIPPING INSULATION SHEATHING FROM AN ELECTRIC CABLE COMPRISING A PAIR OF PIVOTALLY CONNECTED LEVERS, ONE HAVING A CABLE SUPPORTING ASSEMBLY, AND THE OTHER CARRYING A SHEATHING CUTTING ASSEMBLY WITH A CUTTING BLADE EXTENDING TOWARD SAID SUPPORTINH ASSEMBLY, A LINK PIVOTALLY CONNECTED WITH ONE OF SAID LEVERS ENGAGEABLE WITH THE PIVOTAL CONNECTION OF THE LEVERS FOR LIMITING THE CLOSING POSITION OF THE LEVERS AND HAVING A PIN AND SLOT CONNECTION WITH THE OTHER LEVER LIMITING THE MAXIMUM OPENING POSITION OF THE LEVERS WITH RESPECT TO EACH OTHER, AND MEANS COOPERATING WITH SAID LINK FOR ADJUSTING AND LIMITING THE OPEN POSITION OF THE LEVERS TO POSITION THEM IN ACCORDANCE WITH THE SIZE OF THE CABLE TO BE OPERATED UPON BETWEEN THE AFORESAID OPENING AND CLOSING POSITIONS OF THE LEVERS. 